1. Field of the Invention
The present invention relates to information processing apparatuses and methods, information recording media, and computer programs. More particularly, the invention relates to an information processing apparatus and method, an information recording medium, and a computer program in which various items of content whose usage needs to be managed are stored and the usage of each data unit forming the content is managed.
2. Description of the Related Art
Various types of software data (hereinafter referred to as “content”), for example, audio data, such as, music, image data, such as movies, game programs, and various application programs, can be stored in recording media, such as Blu-ray discs using blue-violet lasers, digital versatile discs (DVDs), mini discs (MDs), or compact discs (CDs) as digital data. In particular, Blu-ray discs can implement high-density recording, and can record large-capacity video data as high quality data.
Such various information recording media storing digital content are provided to users. The users play back the content by using a personal computer (PC) or a playback device, such as a disc player.
Generally, the distribution rights of many items of content, such as music data and image data, are owned by creators or sellers of the content. Accordingly, when distributing the content, certain measures are taken, such imposing as certain usage restrictions, to prevent unauthorized copying by permitting the usage of the content only to authorized users.
Digital recorders and recording media allow repeated recording and playback operations without the loss of image or sound quality. Accordingly, the distribution of the content which is copied without authorization via the Internet, the distribution of pirate discs, for example, CD-Rs, storing content, or the use of copied content stored in a hard disk, such as in a PC, is widespread.
Large-capacity recording media, such as DVDs and recently developed recording media using blue-violet lasers, can record a large amount of data equal to one or several movies on a single medium as digital information. As the recording digital information, such as video information, becomes common, it is important to consider the protection of copywriters by preventing unauthorized copying. To prevent unauthorized copying of digital data, various techniques for preventing unauthorized copying have been adopted in digital recorders and recording media.
For example, a content scramble system is employed for DVD players. In this system, video data or audio data is recorded on a DVD-read only memory (DVD-ROM) by being encrypted, and a key for decrypting the encrypted data is supplied to licensed DVD players. A license is provided only for DVD players that are designed based on predetermined operation rules, for example, complying with the rule for not performing unauthorized copying. A licensed DVD player decrypts the encrypted data recorded on a DVD-ROM by using the provided key, thereby playing back images or sound from the DVD-ROM.
On the other hand, a DVD player without a license is not allowed to decrypt the encrypted data recorded on the DVD-ROM since it does not have a key for decrypting the data. In this manner, in the content scramble system, DVD players which do not satisfy the required conditions for receiving a license are not allowed to play back digital data recorded on a DVD-ROM, thereby preventing unauthorized copying.
Due to the widespread use of data communication networks, so-called home networks, in which household electric appliances, computers, and peripheral devices are connected in a household via a network so that they can communicate with each other, are becoming common. In the home network, devices communicate with each other to share the data processing functions of the devices, and content can be sent and received between the devices, thereby providing a convenient and comfortable environment to the users. It is expected that home networks will become more widespread.
Because of the development of networking described above, content stored in information recording media is frequently accessed from devices connected to a home network. The above-described known system for preventing unauthorized copying is based on the concept that one license is given to one player. Accordingly, no consideration has been sufficiently taken for handling the processing for accessing a device in which a recording medium is installed, such as a home server or a player, connected to a network from another network-connected device, such as a PC or a television, and for playing back content from the accessed device via the network.
In the past, since one item of content stored in a recording medium was played back in one player, it was sufficient to manage the usage of the content by providing a content usage right, such as a license, to the content or a player. Currently, however, due to the progress of large-capacity information recording media and the digitization and networking of household electric appliances, a content usage management system different from the one in the past becomes necessary. More specifically, a content usage management system satisfying the following requirements is demanded:
(1) recording a plurality of items of content on a recording medium and conducting different types of management for the usage of the individual items of content;
(2) using content in a specific network, such as a home network, i.e., playing back content by a network-connected device or accessing a home server and copying content stored in the home server; and
(3) distributing information required for playing back content, such as a key for decrypting content, to specific users via a network with high security.